Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterised by unexplained and persistent or recurrent incapacitating fatigue accompanied by a variety of symptoms and substantial reductions in previous levels of occupational, educational, social and/or personal activity [1,2]. Given the absence of biomarkers for diagnosis, ME/CFS is defined by a combination of symptoms, most of which are non-specific and common to a number of diseases and conditions.
Over 20 case definitions have been proposed, leading to large variations in sensitivity and specificity of diagnosis. These diverse sets of diagnostic criteria and distinct ways in which they have been applied pose significant problems, as research results may vary considerably according to which definition is used. A particular problem occurs when overly inclusive criteria are used, since their lack of specificity may lead to considerable selection bias [3,4].
Unfortunately, many studies, clinical trials in particular, have used broad case definitions such as the Oxford criteria , which requires little more than the presence of persistent significant fatigue for over six months and the exclusion of conditions that could explain symptoms, for a diagnosis to be made.
This problem has been highlighted by the Agency for Healthcare Research and Quality (AHRQ) review of evidence for the NIH Pathways to Prevention Workshop , which showed significant changes to the interpretation of evidence for treatment, when studies using broad case definitions, such as the Oxford criteria, are excluded from the analysis. The implications for clinical practice suggest that fit-for-all management approaches to ME/CFS, may be inadequate for patients who fulfil better targeted case definitions.
For patients selected using more restrictive definitions, cognitive behavioural therapy (CBT), graded exercise therapy (GET) and other forms of non-drug management approaches to ME/CFS are most appropriate as adjunct therapies rather than restorative treatments, when provided by therapists with a good understanding of ME/CFS. These forms of behavioural intervention have been shown to support the well-being and rehabilitation of those suffering from many chronic and disabling conditions . However, it is very important that the use of behaviourally based management strategies does not deter researchers, physicians and other health professionals from the overarching goal of investigating the causes and pathophysiology of ME/CFS in various sub-groups and the development of specific treatments.
Differing case definitions point to the need for an accurate diagnosis of myalgic encephalomyelitis/ chronic fatigue syndrome by Luis Nacul, Caroline C. Kingdon, Erinna W. Bowman, Hayley Curran & Eliana M. Lacerda in Fatigue: Biomedicine, health & behaviour [Published online 8 Jan 2017]